The 34-year-old actress and her rocker husband, Christopher Jarecki, welcomed their boy in Los Angeles on May 5. Bear Blu (whose quirky name was suggested by Silverstone's mother-in-law) weighed in at 7 pounds, 15 ounces, and "had crazy amounts of hair when he came out," Silverstone tells Us. "He's really calm."

And the "Clueless" star and "Kind Diet" author says she went into full-on nesting mode after Bear Blu made his grand entrance. "I didn't leave the house at all for six weeks after his birth," Silverstone tells Us. "I wanted to soak in every moment of his scrumptiousness."

And hubby of six years Jarecki loves being a parent, too.

"We all take baths together sometimes," she notes.

For more exclusive photos of Silverstone's adorable baby boy and details about his first nine weeks, pick up the new Us Weekly, out now!